Direct-current machine with compensating pole-face windings



y 8, 1956 H. RIMKUS 2,745,031

DIRECT-CURRENT MACHINE WITH COMPENSATING POLE-FACE WINDINGS Filed May 17. 1952 Fi 2 6 w 10 r flu 00o 4 3 7 Int e for:

United States Patent Siemens- Schuckertwerke Aktiengesellschaft, Berlin- Siemensstadt, Germany, a corporation of Germany mfi' y 17, 1952, Serial No: 288571 Claims prlority, application Germany M y-' 1951' S C-11mins. (Cli Sill- 21 My invention relates to dynamoelectric direct-current machines with compensating pole-face windings.

The compensating. windings insuch machines, for instance railway motors, are often disposed inslots of the pole shoes so that the windings connect the pole shoes with each othert Ifa-defect'occurs-in one of the excitation coils of a pole, itis difiicult to remove the coil because this can be done only after disconnecting the compensatingwinding 7 It is anobject of my invention to -improve such machines toward better accessibility" of the pole excitation coils and greater ease of assembling and disassembling tlie' compensatingpole-face windings;

1- 0 this.-end,-a-nd-in accordance" with my invention, a direct-current machine-with compensating windings disposed in" slbts' of the pale shoes, has its polestructures composed of a core portion and a pole shoe portion which form separate structural units and are separably joined with each other to readily permit removing the pole core with its excitation coil without requiring the pole-shoe winding to be disconnected from the corre sponding windings of the adjacent poles.

According to a specific feature of the invention, the readily separable junction between the pole shoe and the pole core is effected by means of screw bolts which traverse the pole core and engage screw thread means in the pole shoe. In machine designs where the pole shoe cannot be provided with reliable screw thread means be cause the space available above the compensating winding is insufficient for this purpose, the compensating winding given a non-uniform distribution which, however, is symmetrical to the axis of the pole, so that in the middle of the pole shoe a relatively wide tooth of material remains available for providing a satisfactory thread.

According to a more specific feature of the invention, the pole shoe may be attached by giving its compensating winding the just-mentioned non-uniform distribution and providing the middle portion of the pole shoe with a groove which extends in the longitudinal direction of the pole and receives a bar equipped with the threaded bores for engagement by the fastening screws.

According to still another feature of the invention, a bar is inserted into a center groove of the pole shoe, and this bar carries a screw bolt which passes through the pole shoe, the pole core and the machine housing, to engage a screw nut located in a recess of the housing. The bar and the bolt may consist of an integral piece of material or the bolt may be welded to the bar.

The foregoing and other features of the invention will be apparent from the embodiments exemplified by the drawing. The illustrations show only one of the pole portions of the respective machines since in other respects, not essential to the invention, the machines may have any of the customary or known designs.

Fig. 1 shows a sectional front view of a pole structure with a portion of the adjoining yoke or housing of the machine;

Fig. 2 illustrates a sectional view of another embodimentiand Fig. 3 is a cross section through. the pole structure according. to Fig.1 2'.

The'pole structure accordingto Figs. 1 and 2 has a-pole core consisting, for instance, of a solid body of iron. The core carries an excitation coilv I of approximately the same height-as the core. Attached to the pole core isa pole shoe 3' of'laminatediron. The pole shoe has a number of slots or grooves 4 non-uniformly distributed along its periphery. Howeventhe grooves in eachpole shoe are symmetrical to the pole axis in such a manner that a. relatively wide tooth of material remains in the middle portion of the pole shoe. These slots receive the rods (not illustrated) of the compensating winding. The winding is connected with the windings of the adjacent cores. A bolt screw 5 serves for removably attaching the pole shoe 3' to the core 2.

According to Fig. l, the pole shoe 3 is provided with a groove into which a cross bar 7 is inserted. Thiscross bar has threaded openings for engagement by the screw bolt 5: The screw 5 passes through a bore of the yoke or housing 6 andalso through a bore of the pole core 2 to enter intothreaded engagement with the crossbar 7. It is generally preferable to provide a plurality of the above-described fastening screws 5.

If in an assembled machine a defect occurs in one of the pole excitation coils 1, the corresponding screws Scan readily be removed, thus severing the mechanical connection of the core with the yoke and with. the pole shoe. The pole core with its coil'can then be pulled out of the machine for inspection or repair without necessit'atin'g a" disconnection of the" compensating pole shoe winding;

The'embodiment acc'or'ding'to Figs. 2' and? is to some extent similar to that of Fig. 1, similar elements being denoted by the same respective reference numerals in all figures.

In the embodiment shown in Figs. 2 and 3, the pole shoe 3 has a center groove with an inserted cross bar 7. Firmly joined with this cross bar are two screw bolts 10 which pass freely through the pole shoe, the pole core and the magnetic yoke 6 of the machine. The upper ends of the screw bolts are threaded and enter into respective screw nuts 11 disposed in respective recesses at the outside of the yoke or housing. This design has the advantage of saving space for the compensating winding. The bolts 10 and the bar 7 may be made of one integral piece of material, or they may be welded together. While a single bar 7 may be used for each pole shoe, two or more separate bars 7, each having one screw bolt 10, may be provided, as is the case in the embodiment represented in Fig. 3.

When manufacturing a machine according to this design, the individual pole shoes may be mounted on a jig. Then the compensating windings may be inserted into the slots and the slots may thereafter be covered or sealed. The entire system, comprising the pole core with its coil and the pole shoe with its winding, can then be readily assembled with the yoke portion of the machine.

To save space, it is usually preferable to join the laminations of the pole shoe by rivets whose diameter is as small as permissible. This is the case with the rivets 12 and 13 that traverse the laminated pole shoe structure according to Fig. 1. The individual sheets of which the laminated pole shoe is composed, and which are secured together by such thin rivets, may be additionally fastened together by cementing. The thus cemented laminations are schematically indicated in Fig. 3 by vertical cross hatching. Especially suitable as a cementing medium between the individual laminations is a solvent-free cement that polymerizes when subjected to heat treatment.

I claim:

1. A dynamoelectric direct-current machine, comprising a machine housing structure and pole structures mounted on said housing structure, each pole structure having a pole core and a rpole shoe in mutual coaxial alignment, said core having a pole excitation coil, said pole shoe of each pole comprising a rigid unitary'iron structure having an even number of at least four peripherally sequential compensating winding grooves, said grooves being equally divided at each side of the pole axis, said core and said pole shoe comprising two separate parts and having respective junction faces outside said excitation coil, a radially extending screw bolt axially traversing said pole core and including means removably fastening said pole shoe and said core to said housing, said pole shoes each having a central longitudinal groove open to the radial magnetic air gap of the machine and extending from one side to the other of its respective shoe, and a clamp bar disposed in said longitudinal groove, said screw bolt being secured to said clamp bar.

2. A dynamoelectric direct-current machine, comprising a machine housing structure and pole structures mounted on said housing structure, each pole structure having a pole core and pole shoe in mutual coaxial alignment, said core having a pole excitation coil, said pole shoe of each pole comprising a rigid unitary iron structure having an even number of at least four peripherally sequential compensating winding grooves, said grooves being equally divided at each side of the pole axis, said core and said pole shoe comprising two separate parts and having respective junction faces outside said excitation coil, a radially extending screw bolt axially traversing said pole core and including means removably fastening said pole shoe and said core to said housing, said pole shoes each having a central longitudinal groove open to the radial magnetic air gap of the machine and extending from one side to the other of its respective shoe, and a clamp bar disposed in said longitudinal groove, said screw bolt being 4 1 i V I secured to said clamp bar, the width of said clamp bar being substantially equal to the cross-sectional diameter of said bolt.

3. A dynamoelectric direct-current machine, comprising a machine housing structure and pole structures mounted on said housing structure, each pole structure having apole core and a pole shoe in mutual coaxial alignment, said core having a pole excitation coil, said pole shoe of each pole comprising a rigid unitary iron structure having an even number of at least four side-toside peripherally sequential compensating winding grooves, said grooves being equally divided at each side of the pole axis and so spaced as to define at said division a tooth in said pole structure wider than the teeth defined therein between said side grooves, said pole shoes each having a central longitudinal groove open to the radial magnetic air gap of the machine and extending from one side to the other of its respective shoe, a clamp bar disposed in said longitudinal groove, and a radially extending screw bolt axially traversing said pole core and including means for removably fastening said pole shoe and said core to said housing.

References Cited in the file of-this patent Great Britain .4 Sept. ,9, 1949 

